rxrpc: Don't try to map ICMP to error as the lower layer already did that

In the ICMP message processing code, don't try to map ICMP codes to UNIX
error codes as the caller (IPv4/IPv6) already did that for us (ee_errno).
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/ar-error.c

@@ -151,28 +151,18 @@ void rxrpc_UDP_error_handler(struct work_struct *work)
 			switch (ee->ee_code) {
 			case ICMP_NET_UNREACH:
 				_net("Rx Received ICMP Network Unreachable");
-				err = ENETUNREACH;
 				break;
 			case ICMP_HOST_UNREACH:
 				_net("Rx Received ICMP Host Unreachable");
-				err = EHOSTUNREACH;
 				break;
 			case ICMP_PORT_UNREACH:
 				_net("Rx Received ICMP Port Unreachable");
-				err = ECONNREFUSED;
-				break;
-			case ICMP_FRAG_NEEDED:
-				_net("Rx Received ICMP Fragmentation Needed (%d)",
-				     ee->ee_info);
-				err = 0; /* dealt with elsewhere */
 				break;
 			case ICMP_NET_UNKNOWN:
 				_net("Rx Received ICMP Unknown Network");
-				err = ENETUNREACH;
 				break;
 			case ICMP_HOST_UNKNOWN:
 				_net("Rx Received ICMP Unknown Host");
-				err = EHOSTUNREACH;
 				break;
 			default:
 				_net("Rx Received ICMP DestUnreach code=%u",